Originally published on the Discovery Islander

“Noise is the amount of disagreement between people who make professional judgements.” This is the definition supplied by Daniel Kahneman, a behavioural scientist and Nobel Prize winner, and his two fellow scientists, Olivier Sibony and Cass Sunstein, who were trying to understand and explain why “a lot of professional judgement actually has no connection to reality.”

Their studies were initially inspired by a survey of 208 federal judges in the United States. On convictions for the same offence that received an average of 7 years incarceration, sentences varied by as much as 50%. Another study found that the value estimates of insurance underwriters varied by 55%, a large enough range that made their assessments almost useless. Psychiatry is particularly “noisy”. So is forestry.